Following are a few insect situations that are worthy of note. More information will be provided as the situations develop.|
· First-generation bean leaf beetles are showing up in soybean fields, especially in northern Illinois. Steve Doench, agronomist with Pioneer Hi-Bred International, found more than 120 bean leaf beetles per 20 sweeps in Bureau County on July 10. Defoliation was 10 to 15% at that time. Although we have not encountered the densities of bean leaf beetles that have been observed in Iowa in recent years, we need to remember that bean leaf beetles are capable of causing significant defoliation.
· According to several reports, grasshoppers and potato leafhoppers have "exploded" in some areas. Although numbers of grasshoppers cannot increase at this time of year, their activity certainly can become more evident in crop fields. Potato leafhopper numbers, on the other hand, can increase significantly during hot, dry weather. Watch for grasshoppers in both corn and soybeans, and watch for potato leafhoppers in both alfalfa and soybeans.
· Reports of insects interfering with weed control have been common this year, and we continue to gather information. Mike Roegge, Extension unit educator in crop systems in Quincy, observed beetle larvae in waterhemp and smartweed in Adams County. Control of these weeds with Cobra, Distinct, Roundup, and First Rate was compromised. Matt Montgomery, Extension unit educator in crop systems in Springfield, found stalk borers and beetle larvae in ragweed in Sangamon County. Aaron Hager, with the assistance of some of our graduate students, found stalk borers in giant ragweed and beetle larvae in marestail.
I first mentioned this issue in issue no. 12 (June 14, 2002) of the Bulletin. In issue no. 14 (June 28, 2002), I indicated that Mark Hoard, Extension educator in IPM in Mt. Vernon, had identified the larvae as members of the family Antrhibidae (fungus beetles). We are continuing to gather specimens of these insects and will get more information about them in the near future.
Keep the reports coming. The information you provide to us can help others.--Kevin Steffey